Which row represents thny 4q5lp+2 gfy 5du8wze enthalpy change for condensation and sublimation phase changes?dwn 854 +pyfyl5z q2gu

  Which of the following is true irzcb ih42fk c7*l,j;mn exothermic reactions?

  Which of the following is correct in an endothermic reac3-60 t cnxj2fc qwh/: 1fyjd.jb7uwfbtion?

  If a reaction is endoth 4ilt,v5mp rqke)b2*permic:

  Which statement is true for an endothermic reaction that results in an increase in entropy?

  The enthalpy diagram below shows +ff b +):d4pg)ch. zjeann, v0d 9fjuythat:

  A block of nickel of mass m=70g whose initial temperatn2.l:8 r+v ynzcg/ed8hizni+s7iac2ure $T_1$=18.70${}^{\circ }C$, absorbs 350J of heat. Given that the specific heat capacity of Ni is approximately 0.50Jg${}^{-1}$K${}^{-1}$ calculate the final temperature of the block $T_f$, in ${}^{\circ }C$.

  The following diagram shows the enthalpy of the rea/sw z63hb/gpy ctants and products of a reaction involving gaseous covalent c 6whygs/b/3zpompounds. Which statement is correct?

  When a small amount of solid sodium hydroxide is added to a sample of di.jp n d6ynh,*klute hydrochloric acid, an exothermic reaction takes pl nj.* ,ydkp6hnace.
The following graph shows the temperature of the acid during the reaction. The cooling of the solution after the initial reaction follows an approximately linear trend, as indicated by the dotted line.

What value for the temperature change, ΔT, should be used to calculate the change in energy, q, during the reaction? q=mcΔT

  A given mass of magnemz:d p* 73i x nw bzw40trapzd/.5j*nbsium was added to 500cm${}^3$ of aqueous hydrochloric acid in a Styrofoam cup to form magnesium chloride. The temperature at the start was 18${}^{\circ }C$ and after the magnesium had dissolved, the temperature rose to 20${}^{\circ }C$
1.State a balanced chemical equation for this reaction. Mg+  HCl → MgCl${}_2$ + $H_2$
2.Given that the change in enthalpy, ΔH is0.185kJ and the specific heat capacity of water is 4.18Jg${}^{-1}$K${}^{-1}$, calculate the mass of magnesium added to the hydrochloric acid. m=   g.
3.Determine the systematic errors caused by the use of styrofoam cups.

  Which of the four reactions below is an ef56u*+t;qy)qngtgw xgbi*v7 h 2 1s ysndothermic reaction?

  When a 2.80g of anhydrous copper sulfate sample, zku *y-b0 y(vd$CuS{O}_4$ was added to 20.0g of water in a calorimeter, a rise in temperature of 15.0${}^{\circ }C$ was recorded.
Given that the specific heat capacity of water is 4.18J$g^{-1}{K}^{-1}$;
1.Define specific heat capacity.
2.Calculate the change in enthalpy in kJ. q=  kJ.
3.Calculate the number of moles of copper Sulfate. n($CuS{O}_4$)=  mol.
4.Calculate the molar enthalpy of reaction.ΔH= -  kJ\mol${}^{-1}$

  The temperature of dilute sulphuric acid rises when it reacts with zinc accordi7vmb)6it)8rtzo 7laxd ; 4dzwng to the followibal)x rtz wv ;8mdd74t)zoi 67ng chemical equation:

1.State whether the reaction is  ----待选择----exothermicendothermic .
2.Explain what this implies in terms of the chemical potential energy contained in the reactants and the products.
3.Draw an energy level diagram for this reaction.

  Which reaction below is endwbq-k +kv; wu 6xpp6n-othermic?

  When a sample of solimoqo z k-is8 c90bfq8 ,tw,kxu8z9- hwd calcium carbonate is placed in hydrochloric acid, the following reaction t9zmx0 c -uw 8sft,qob9h-q8ikzo,w8kakes place.
$CaC{O}_3$(s)+2HCl(aq)→$CaC{l}_2$(aq)+$H_{2}O$(l)+$C{O}_2$
The temperature and mass of the solution are both monitored, as shown.

1.The standard enthalpies of formation of hydrochloric acid and the products of its reaction with calcium carbonate are shown.


.1.Define the term standard enthalpy of formation.
.2.Calculate the standard enthalpy of formation of calcium carbonate, in kJmol${}^{-1}$.
2.A reaction profile shows how the enthalpies of the molecules in a reactant change as the reaction progresses.
Part of the reaction profile for the reaction of calcium carbonate and hydrochloric acid is shown.


Complete the reaction profile by showing how the enthalpy changes between the reactants and products and labelling the value of Δ$H_r^{\Theta }$.

3.The sample of calcium carbonate is added to 100 cm${}^3$ of dilute hydrochloric acid. During the reaction, the mass of the conical flask and its contents decreases by 6.28g due to the loss of carbon dioxide gas. The molar mass of carbon dioxide is 44.0g mol${}^{-1}$.

.1.Calculate, to 1 decimal place, the maximum possible change in the temperature of the solution, using sections 1 and 2 of the data booklet. You should assume that the solution has the same density and specific heat capacity as water and does not change in mass during the reaction.ΔT=(+)  ( ${}^{\circ }C$ ).

.2.The measured change in temperature is much less than the maximum possible value. State why the experimental and theoretical results are different, assuming that the value of Δ$H_r^{\Theta }$, is accurate.
.3.Suggest why the measured mass loss during the reaction is likely to be less than the mass of carbon dioxide produced.

  In the presence of a catalyst, aqueous hydrogen peroxide decomposes into water a ri,*9p kkxi4ond oxygen. The equation for this reaction and the enthalpy change * 9oikp4ixk r,
ΔH${}_{dec}^{\theta }$ is related to three other enthalpy changes,ΔH${}_A^{\theta }$,ΔH${}_B^{\theta }$ and ΔH${}_C^{\theta }$.

.1.State the name given to the enthalpy change labelled ΔH${}_A^{\theta }$.The name is    (of aqueous hydrogen peroxide)

.2.Calculate ΔH${}_A^{\theta }$ in kJ mol${}^{-1}$ using the information in the enthalpy cycle and section 12 (Section 13- 2025 Syllabus) of the data booklet.ΔH${}_A^{\theta }$=  kJ mol${}^{-1}$.

2.A solid catalyst was added to 100 cm${}^{-1}$ of an aqueous hydrogen peroxide solution and the temperature was monitored using a thermometer. The resulting temperature-time graph is shown.




The maximum theoretical temperature change during the reaction, ΔT, is determined by the molar concentration of hydrogen peroxide,[$H_2{O}_2$]
.1.State why ΔT is determined by extrapolating the trend of the temperature profile between 65 and 120 s.
.2.Using the value of ΔH${}_{dec}^{\theta }$ the information in the temperature-time graph and sections 1 and 2 of the data booklet, calculate the initial concentration of the hydrogen peroxide solution in mold\m${}^{-3}$.
Assume that the specific heat capacity of the solution is 4.18J g${}^{-1}$K${}^{-1}$. [$H_2{O}_2$] =  mold\m${}^{-3}$.
3.The decomposition of gaseous hydrogen peroxide into water vapour and oxygen is an important atmospheric reaction.
.1.Calculate the enthalpy change of this reaction, using the bond enthalpy values in section 11 (Section 12- 2025 Syllabus) of the data booklet.
Enthalpy change=-  (kJmol${}^{-1}$)
.2.Suggest one reason why the enthalpy change calculated in (i) differs from the enthalpy change for the decomposition of aqueous hydrogen peroxide.

  The following graph represents the change of conc05cm1ylbyxsr48ij n;a z9 q2xentration of a gaseous reactant and gaseous product during a reaction. At t=10mins, the temperature is increased and at t=15mins, the volume of the reaction vessel8;nrxy1qx542i zsyl jmc9a0b is increased.

  Sulfur dioxide ($S{O}_2$) reacts with oxygen and sulfuric acid($H_{2}S{O}_4$) to produce oleum($H_2{S}_2{O}_7$) in two reaction steps. The enthalpy cycle for this process is shown.

This process is used to produce a dilute solution of oleum in 5000g sulfuric acid from 0.80 mol sulfur dioxide. During the reaction, the temperature of the sulfuric acid increased by 22.8${}^{\circ }C$.
What are the enthalpy changes of the second step,ΔH${}_2$, and the overall process, ΔH${}_{t}otal$, assuming no heat is lost during the reaction?
·Specific heat capacity of $H_{2}S{O}_4$,c=1.60Jg${}^{-1}$K${}^{-1}$;
·q=mcΔT.

  Colorimetry was used to defis3n1,ld ;sdcc1 kr i: f3 :.sy6uasbtermine the change in color for the below system at eqd .kb c ;1 is6fs33uysl :c1irn,a:sfduilibrium as temperature increases.
Which statement(s) is/are correct for the following reaction?


I.The forward reaction is exothermic
II.The backward reaction absorbs energy
III.$K_c$ decreases with increasing temperature

  The standard enthalpy of formation of gaseous nitxf t:mxb4cpo ) 0r.z.rric oxide,ΔH${}_f^{\theta }$(NO(g)),is +kJmol$-1$.
1.Write a reaction equation, including state symbols, corresponding to the standard enthalpy of formation of gaseous nitric oxide.
$\frac{1}{2}$$N_2$(g)+$\frac{1}{2}$$O_2$(g)→   (g)
2.Calculate the bond enthalpy of nitric oxide, using the value of ΔH${}_f^{\theta }$ (NO(g)) above and section 11 (Section 12- 2025 Syllabus) of the data booklet.
3.In the Ostwald process, nitric oxide (NO) is reacted with oxygen and then water to produce aqueous nitric acid ($HN{O}_3$) The overall equation and enthalpy change of this reaction are given below.
4NO(g)+3$O_2$(g)+2$H_{2}O$(l)→4$HN{O}_3$(aq)
ΔH${}_1$=-576.4kJmol${}^{-1}$
Calculate the enthalpy of formation of aqueous nitric acid, ΔH${}_f^{\theta }$(HNO${}_3$ (aq)), using the values of ΔH${}_f^{\theta }$ (NO(g))= +90.3kJmol$-1$,and
ΔH${}_1$ and section 12 (Section 13- 2025 Syllabus) of the data booklet.
4.The nitric oxide used in the Ostwald process is formed by reacting gaseous ammonia (NH${}_3$) with oxygen. The equation and enthalpy change of this reaction are given below.
$4NO(g)$+$5O_2(g)$→$4NO(g)$+$6H_{2}O(g)$
ΔH${}_2$=-906.0kJmol${}^{-}1$
The yield of the Ostwald process may be lower than expected if some of the nitric oxide product reacts with the remaining ammonia. The equation for this side reaction is shown.
$4NO(g)$+$6NO(g)$→$5N_2(g)$+$6H_{2}O(g)$
1.Calculate the enthalpy change for the side reaction, ΔH${}_{side}$=-  (kJmol${}^{-1}$);using the values of ΔH${}_f^{\theta }$ (NO(g)) and ΔH${}_2$.
2.Suggest how the value of ΔH${}_2$ would differ if water were produced in the liquid phase.